Which one of the following statements best describes the mechanism of action of insulin on target cells? (Delhi PG 2010)
|A|| Insulin binds to cytoplasmic receptor molecule and is transferred as a hormone receptor complex to the
nucleus where it acts to modulate gene expression.
|B|| Insulin binds to a receptor molecule on the outer surface of the plasma membrane and the hormone
receptor complex activates adenylate cyclase through the Gs protein.
|C|| Insulin binds to a transmembrane receptor at the outer surface of the plasma membrane, which
activates the tyrosine kinase that is the cytosolic domain of the receptor.
|D||Insulin enters the cell and causes the release of calcium ions from intracellular stores.|
- Enzymatic Receptors have two sites, the drug binds on the extracellular site and the intracellular site has enzymatic activity (mostly tyrosine kinase).
- This enzyme can be activated via JAK-STAT pathway. Insulin, growth hormone, prolactin and cytokines act via enzymatic receptors.